foo.cc: In function 'int main()':
foo.cc:10:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
foo.cc:11:37: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (int i = n ; i >= 0; i--) scanf("%d", &arr[i]);
                                ~~~~~^~~~~~~~~~~~~~~

自豪的采用 HydroJudge 进行评测(github.com/hydro-dev/HydroJudge)

{"receive":"2020-08-15T12:26:39.041Z","handle":"2020-08-15T12:26:39.041Z","cache_start":"2020-08-15T12:26:39.047Z","read_cases":"2020-08-15T12:26:39.178Z","judge":"2020-08-15T12:26:39.181Z","done":"2020-08-15T12:26:39.595Z"}